ศาสตร์เกษตรดินปุ๋ย : ขอบคุณแหล่งข้อมูล : หนังสือพิมพ์ The Nation
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The new generation of anti-histamines acts on our allergies but without making us doze at our desks
More than 600 million people around the world suffer from allergic rhinitis so if you are sneezing while reading this, you are hardly alone.
While the condition is rarely life threatening, its symptoms, which can range from streaming eyes, sneezing and unsightly and itchy blotches to severe breathing difficulties, have a substantial impact on the health and quality of life. The good news is that help for allergy patients is now available through a new non-sedating generation of anti-histamines that if taken properly, can cure different types of allergies and asthma.
Professor Ralph Mosges, chairperson of the ENT Section at The European Academy of Allergy and Clinical Immunology and of the International Standardisation Committee for the Objective Assessment of the Upper Airways, flew into Bangkok recently to talk about the latest medications for allergy control.
Allergic rhinitis, he began by noting, is frequently under-diagnosed and undertreated, while urticaria is often inappropriately managed.
“Allergies or allergic diseases are a hyper-reactivity of our immune system, which reacts toward such allergens as pollens, house dust mites and pet dander. The number of allergic patients has been increasing steadily over the last four decades and many patients are found in industrialised countries and where standards of hygiene are high. Moreover, weather and exhaust gases from vehicles and industrial factories are factors that trigger allergic symptoms and render allergies more aggressive,” he explains.
“In the US and Western Europe, more than 50 per cent of children have sensitisation to one or more allergens. And there are many types of allergy, for example, allergic rhinitis, food allergies and urticaria, which cause symptoms like a blocked or running nose, itching, sneezing, red eyes and tearing. The danger here is that asthma can develop and become a disabling disease.
“These symptoms are caused by a substance known as histamine, which the body releases to react to the allergens it receives as it tries to get rid of these or prevent the body from receiving more.”
Surprisingly, the highest sensitisation levels are found in Singapore where for the most part, they are caused by house dust mites.
“Singapore is an industrialised country. It has a high standard of hygiene and while hygiene is of course beneficial in terms of preventing infectious diseases, it can be detrimental in terms of allergies as our immune system hyper-reacts to some allergens in very clean and industrialised environments with a warm and humid, climate,” he explains.
“Our data show that 75 per cent of the population has sensitisation and about 40-50 per cent have clear symptoms of an allergy to house dust mites allergy as well as asthma.
“Data also show that house dust mites are now found in Greenland. You’d think that once you were close to the North Pole, the cold would prevent them but that’s not the case. The bad news is that dust mite are found everywhere from the pole to the equator. The good news is that there are drops and tablet that you can take for three years to get full relief,” Mosges says,
Another factor that causes allergy is genetics. The odds of developing allergies is six times higher when the mother suffers from an allergy though only twice as high if the father has one. And if both parents have allergies, the odds go up to 8-9 times higher than for a normal child. While passing allergies from parents to their children cannot be prevented, experts agree that breast feeding the child for at least 4-6 months decreases that risk. Also, during pregnancy, the mother should avoid food that contains allergens such as cow milk and seafood.
Guidelines for treating allergies involve avoiding the allergen to which the patient is sensitised, keeping the environment clean and seeking medical treatment if necessary. First-line treatment is one or more anti-histamines, which can be in tablet, eye-drop or nasal-spray form depending on the symptoms. For a patient with severe symptoms, a nasal wash or spray containing steroids may be used.
“Anti-histamines block the histamine receptor at the nose, at the eye and also the lower airways. That’s why anti-histamines are so important in our treatment. They work quickly too, with the patient feeling relief within 10-30 minutes,” Mosges says.
“For inflammatory disease there is the corticosteroid group, usually in the form of a nasal spray. It doesn’t work immediately so the patient won’t feel relief on the first day but the inflammation will be regulated within a week.
There is also is a specific treatment called immunotherapy but while it is effective, it can take years before the full effect is seen and it is also a lot more expensive. In this case, the doctors adjusts the patient’s immune system to the allergen, starting from injecting low doses of the allergen so the body can adapt, then increasing the dose until the body no longer reacts.
This method might take from one to three years but it is effective and also decreases the chance of the disease developing into asthma.”
Urticaria, more commonly known as hives, is a skin allergy also caused by the release of histamine. The symptoms are red or white itchy bumps or wheals on skin. The symptoms come and go. Urticaria is not a lethal disease but it makes the patient uncomfortable and interferes with sleep. This can also be cured by giving anti-histamines, but the patient needs a dose two or four times higher than that used for allergic rhinitis. And because classic anti-histamines have a sedative potential, taking such a high dose is going to make the patient feel sleepy and unable to function properly.
“We now have a new generation of anti-histamines that are endorsed by the international therapeutic guidelines. The dose is higher than the classic one but the drugs have no sedative potential or other nasty side-effects,” he says,
While eating a healthy diet and exercising are important to strengthening the immune system, they have little effect on allergies. “Making immunity stronger is not an option because with an allergy, the immune system is overacting. However, those with a strong immune system are not so prone to developing cancer,” Mosges explains.
“The first year of life is decisive in terms of whether the immune system develops in the direction of tolerance or sensitisation so breast feeding is important.
“But for those who do have allergies, certain steps can be taken to ease problems, such as washing hair before going to bed so pollens are removed and you don’t sleep in a pollinated environment. Some allergic patients might have to take medication and it is essential that this is taken on a regular basis. Remember, even if the symptoms are not so dominant, the inflammation is still there and may turn into asthma. This is a chronic disease. The modern medication is completely safe nowadays and can be taken for years. But you must take it regularly and |not just when needed.”
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